Methods for operating a fuel cell system

ABSTRACT

Purge valves that are manually turned ON but are automatically or electrically turned OFF as the fuel cell production of electricity reaches a predetermined level, e.g., steady state or thereabout are disclosed. The purge valve may be opened at system start-up, or may be opened at system shut-down so that the purge valve is armed and the fuel cell system is purged at the next start-up. Also disclosed is an integrated fluidic interface module that contains various fluidic components including one of these purge valves. The integrated fluidic interface module can operate passively or without being actively controlled by a processor. Methods of operating a fuel cell system, wherein the fuel cell system is purged at system start-up, are also disclosed. The purging automatically stops when the anode plenum is fully purged and replaced with fuel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/IB2014/000952 filed Mar. 14, 2014, which is acontinuation-in-part of and claims priority to U.S. patent applicationSer. No. 13/837,410 filed Mar. 15, 2013, the contents of which areincorporated herein by reference in their entirety as if fully set forthherein.

FIELD OF THE INVENTION

This invention generally relates to methods for operating a fuel cellsystem and more specifically to methods for purging or venting the fuelcell system at start-up and for automatically shutting off the fuel cellsystem when no current is drawn from the system.

BACKGROUND OF THE INVENTION

Fuel cells are devices that directly convert chemical energy ofreactants, i.e., fuel and oxidant, into direct current (DC) electricity.For an increasing number of applications, fuel cells are more efficientthan conventional power generation, such as combustion of fossil fuels,as well as portable power storage, such as lithium-ion batteries. Inparticular, one use of fuel cells is to be a mobile power source forportable or mobile consumer electronic devices, such as cell phones,smart phone personal digital assistants, personal gaming devices, globalpositioning devices, rechargeable batteries, etc.

Known fuel cells include alkali fuel cells, polymer electrolyte fuelcells, phosphoric acid fuel cells, molten carbonate fuel cells, solidoxide fuel cells and enzyme fuel cells. Fuel cells generally run onhydrogen (11₂) fuel, and they can also consume non pure hydrogen fuel.Non pure hydrogen fuel cells include direct oxidation fuel cells, suchas direct methanol fuel cells (DMFC), which use methanol, or solid oxidefuel cells (SOFC), which use hydrocarbon at high temperature. Hydrogenfuel can be stored in compressed form or within compounds such asalcohols or hydrocarbons or other hydrogen containing materials that canbe reformed or converted into hydrogen fuel and byproducts. Hydrogen canalso be stored in chemical hydrides, such as sodium borohydride (NaBH₄),that react with water or an alcohol to produce hydrogen and byproducts.Hydrogen can also be adsorbed or absorbed in metal hydrides, such aslanthanum pentanickel (LaNi₅) at a first pressure and temperature andreleased to a fuel cell at a second pressure and temperature. Hydrogencan also be released via thermolysis reaction of a metal hydride such asmagnesium hydride (MgH2).

Most low temperature hydrogen fuel cells have a proton exchange membraneor polymer electrolyte membrane (PEM), which allows the hydrogen'sprotons to pass through but forces the electrons to pass through anexternal circuit, which advantageously can be a smart phone, a personaldigital assistant (PDA), a computer, a power tool or any device thatuses electron flow or electrical current. The fuel cell reaction can berepresented as follows:

Half-reaction at the anode of the fuel cell:H2→2H++2e

Half-reaction at the cathode of the fuel cell:2(2H⁺+2e)+0₂→2H₂0

Generally, the PEM is made from a proton exchange polymer which acts asthe electrolyte, such as Nafion® available from DuPont, which is aperfluorinated sulfonic acid polymer or other suitable membranes. Theanode is typically made from a Teflonized carbon paper support with athin layer of catalyst, such as platinum-ruthenium, deposited thereon.The cathode is typically a gas diffusion electrode in which platinumparticles are bonded to one side of the membrane.

The patent and scientific literatures disclose few complete andcommercialize-able fuel cell systems that include the generation ofhydrogen fuel, the control of the fluidics, the balance of plant and theelectrical power generation. The literatures do not discuss fluidicinterface systems for fuel cells systems, particularly mobile fuel cellsystems. Hence, there remains a need for such fuel cell systems.

SUMMARY OF THE INVENTION

The invention is directed to an integrated fluidic interface system ormodule for a fuel cell system that mates with a fuel source, such ashydrogen, regulates the incoming fuel pressure to a lower pressure thatis usable with the fuel cell and purges the fuel plenum in the fuel cellwhen a user turns the fuel cell system ON or OFF. No other action isrequired from the user. In one embodiment, the integrated fluidicinterface system has a single switch or ON/OFF button to activate allthe fluidic components on the module.

The invention is further directed to a passive integrated interfacesystem or module for a fuel cell system that performs the functiondiscussed in the preceding paragraph without being actively controlledby a controller or micro-processor, without being powered by a powersource other than an ON/OFF activation by the user, the pressure of theincoming fuel such as hydrogen and the electricity generated by the fuelcell. Such power source includes, but is not limited to, internal orexternal batteries, or power from the device that the fuel cell systempowers.

The present invention is also related to methods of operating a fuelcell system, wherein the fuel cell system is purged or vented at systemstart-up. The purging automatically stops when the anode plenum is fullypurged and its content is replaced with fuel. The present invention isalso related to an inventive purge valve that is manually turned ON butis automatically turned OFF as the fuel cell's production of electricityreaches a predetermined level, e.g., steady state or thereabout. Thepurge valve may be opened at system start-up, or may be opened at systemshut-down so that the purge valve is armed and the fuel cell system ispurged at the next start-up. In one embodiment, the inventive purgevalve is mechanically actuated or armed to open and electricallyactuated to close.

The present invention includes a method for operating a fuel cell systemcomprising at least one fuel cell, said method comprises the steps ofactivating a switch and deactivating the switch. The activating stepenables a flow a fuel from a fuel source to the fuel cell and initiatesa venting step of an anode compartment in the fuel cell with said fuel.The venting step continues until the anode compartment is substantiallyvented and the venting step automatically stops when the anodecompartment is substantially filled by said fuel. The deactivating stepstops the flow of said fuel.

The activating step further opens a purge valve, or the deactivatingstep opens and arms the purge valve. The power from the at least onefuel cell stops the venting step, and preferably this power is generatedduring the fuel cell's conditioning period. This power is substantiallyfree of power from other sources. The activating step also connects thefuel cell to a conductive element in the purge valve, which comprises ashape memory alloy wire. The activating step also connects the fuel cellto an external load after the venting step.

The present invention further includes a method of operating a fuel cellsystem comprising at least one fuel cell, said method comprising thesteps of

(a) flowing fuel to the fuel cell system;

(b) connecting the at least one fuel cell to a conductive element in apurge valve;

(c) venting an anode of the at least one fuel cell through the purgevalve;

(d) disconnecting the at least one fuel cell from the purge valve; and

(e) connecting the at least one fuel cell to an external load.

The conductive element comprises a shape memory alloy and the fuel cellheats up the conductive element which retracts and moves the purge valveto a closed position. This method further comprises the step of movingthe purge valve to an open position at the fuel cell system's start-upor at the fuel cell system's shut-down. The disconnecting step (d)occurs without being controlled by a processor or by a person. Thedisconnecting step (d) is electrically actuated and the connecting step(b) is manually actuated.

The present invention is also related to a method of operating a fuelcell system comprising at least one fuel cell and an automatic shut-offvalve, said method comprising the steps of

-   -   (a) opening the automatic shut-off valve;    -   (b) flowing fuel to the fuel cell system to produce an        electrical current;    -   (c) monitoring the electrical current produced by the fuel cell        and transmitted to a consumer device, and    -   (d) when said electrical current is reduced to a predetermined        threshold,    -   (e) connecting the at least one fuel cell to a conductive        element in the automatic shut-off valve to close said shut-off        valve.

The conductive element comprises a shape memory alloy, and preferablythe fuel cell heats up the conductive element which retracts and movesthe shut-off valve to a closed position.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which form a part of the specification andare to be read in conjunction therewith and in which like referencenumerals are used to indicate like parts in the various views andvarious embodiments:

FIG. 1A is a perspective view from a reference surface 22 of aninventive integrated fluidic interface module 10 and FIG. 1B is aperspective view from reference surface 24 opposite to reference surface22 of an inventive integrated fluidic interface module; FIG. 1C is across-sectional view of FIG. 1B;

FIG. 2A is a top perspective view of an exemplary fuel cartridge; FIGS.2B-2C are cross-sectional views of exemplary cartridge shut-off valves;FIG. 2D is a bottom perspective view of an exemplary fuel cell system;

FIG. 3A is a partial exploded view of FIG. 1B; FIGS. 3B-3C arecross-sectional views of FIG. 1B showing an actuation of a moduleinterface port 18;

FIGS. 4A-4D are perspective view of the inventive integrated fluidicinterface module 10 from reference surface 24 showing a sequence ofactuation of module interface port 18 by switch 12;

FIG. 5 is a partial exploded view of FIG. 1B showing the individualparts of pressure regulator 60;

FIG. 6A is a perspective view from a reference surface 22 of theinventive integrated fluidic interface module showing a fuel manifoldand FIG. 6B is a perspective view from reference surface 24 of theinventive integrated fluidic interface module showing a pressurefeedback flow path;

FIG. 7 is a cross-sectional view of an exemplary fuel cell;

FIG. 8A is a partial exploded view from reference surface 22 of theinventive integrated fluidic interface module showing an inventive purgevalve; FIG. 8B is a further partial exploded view of FIG. 8A; FIG. 8C isthe same as FIG. 1C but viewed from reference surface 22 and FIG. 8D isan enlarged view of the purge shuttle of FIG. 8C; FIG. 8E is aperspective view from reference surface 24 of the inventive integratedfluidic interface module showing the purge flow manifold;

FIGS. 9A-9C are three perspective views of the inventive purge shuttle;

FIGS. 10A-10B are similar to FIG. 8C showing the open and closedconfiguration, respectively, of the inventive purge valve; FIG. 10C isan exploded view showing the inventive integrated fluidic interfacemodule with a PC board; FIG. 10D is a cross-sectional view of theinventive integrated fluidic interface with an inverse purge valve.

FIG. 11 is a perspective view of an alternative purge shuttle;

FIG. 12 is a perspective view of an alternative module interface port;

FIG. 13 is a perspective view of another alternative purge shuttle;

FIGS. 14 and 15 are flow charts illustrating inventive methods ofoperating fuel cell systems;

FIG. 16 is a cross-sectional view of another integrated fluidicinterface module;

FIGS. 17A and 17B are perspective view of the integrated fluidicinterface module showing the actuation of same;

FIGS. 18A-C are perspective views of another purge valve in the off, onand release configurations, and FIGS. 18D-F are cross-sectional viewsalong the longitudinal axis of the purge valve shown in FIGS. 18A-C,respectively.

FIGS. 19A-B are perspective views of yet another purge valve in the offand on configurations, and FIGS. 19C-D are cross-sectional views alongthe longitudinal axis of the purge valve shown in FIGS. 19A-B,respectively.

A parts list correlating the reference numbers used in the drawings tothe part names used in the specification is provided at the end of thespecification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Integrated fluidic interface modules of the present invention arefluidic modules that connect a fuel cartridge, such as a methanol orbutane fuel cartridge, hydrogen storage device or hydrogen generator, toa fuel cell, such as PEM fuel cells, DMFC, SOFC or other fuel cells.Integrated fluidic interface modules of the present invention provide adocking port or connection to the fuel cartridge to allow the fuel toflow from the cartridge to the integrated fluidic interface module. Theintegrated fluidic interface modules also regulate the pressure of theincoming fuel to a lower pressure that fuel cells prefer. The inventiveintegrated fluidic interface modules also purge the fuel cells to removeunwanted gases in the anodes of the fuel cells semi-automatically ormanually.

Referring to FIGS. 1A-1C, integrated fluidic interface module 10(hereinafter module 10) is shown from the top side and the bottom side,respectively. Module 10 has switch 12 with an “ON” segment 14 and an“OFF” segment 16. Module 10 also have a module interface port 18 sizedand dimensioned to connect to a fuel cartridge 20 shown in FIG. 2A. Topside 22 and bottom side 24 of module 10 contain a plurality ofmicro-fluidic channels that are described in details below. It is notedthat the terms “top” and “bottom” are relative terms and are used forthe ease of describing the present invention. Surfaces 22 and 24 arereference surfaces designated to aid in the description of the presentinvention. These terms do not necessarily indicate the orientation ofmodule 10 or the fuel cell system as a whole during actual operation.Fuel cartridge 20, module 10 and the fuel cell system incorporatingmodule 10 can operate in any orientation.

FIGS. 2A-2C show an exemplary fuel cartridge 20 and exemplary cartridgeshut-off valves 26 that can be used with module 10. Fuel cartridge 20 isdescribed in published patent applications US 2011/0212374, US2011/0099904, and US 2011/0104021 and U.S. D673,497 and valves 26 aredescribed in published patent applications US 2011/0121220, US2011/0189574, US 2011/0212374 and US 2011/0099904. These references areincorporated herein by reference in their entireties. Module interfaceport 18 comprises outer guard 28 and inner tube 30. Tube 30 is sized anddimensioned to open cartridge shut-off valve 26, shown in FIGS. 2B-2C.Shut-off valve 26 may have a center post 32, which forms a gap 34 withvalve body 36 and/or seal retainer 38. Tube 30 of module interface port18 enters gap 34 to open one or more seal 40. When tube 30 is withdrawnfrom cartridge valve 26, seal(s) 40 re-closes fuel cartridge. 20. Othersuitable shut-off valves 26 usable with module 10 include, but are notlimited to U.S. Pat. Nos. 7,537,024, 7,762,278, 7,059,582 and 6,924,054and published patent application US 2008/0145739.

Outer guard 28 of module interface port 18 is sized and dimensioned tomatch a corresponding channel 42 on cartridge 20. One advantage ofhaving guard 28 and matching channel 42 is to ensure that a proper fuelcartridge is being used with module 10 or fuel cell system 21. Guard 28and channel 42 may have other shapes, such as oval, star, polygonal orany regular or irregular shapes.

FIG. 2D illustrates an exemplary fuel cell system 21 that mayincorporate the inventive module 10. Switch 12 is also illustrated inFIG. 2D. Fuel cartridge 20 may be inserted into an opening in fuel cellsystem 21. Fuel cell system 21 may be a fuel cell charger with a USBcharging port or DC port (shown below in FIG. 10C) on its surface. Fuelcell system 21 may also be a consumer electronic device, a flashlight, aradio, a music player such as a MP3 player, a computer tablet or alaptop. Fuel cell system may have clamp 23 to securely hold cartridge 20therewithin after insertion. Clamp 23 may also be actuated or pushed torelease cartridge 20. In other embodiments, the fuel cell system mayhave other means of coupling cartridge 20 to the fuel cell system; forexample, clips, geometric features such as recesses or bosses, frictionfit, or other coupling mechanisms. The present invention is not limitedto any particular application or usage of the fuel cell system.

Referring to FIGS. 3A-3C, switch 12 interacts with module interface port18 to open valve 26 on fuel cartridge 20. Module interface port 18 haspreferably two knobs 44 disposed on its side opposite from each other.Switch 12 has two corresponding yokes 46 that form a U-shaped end 48adapted to fit around knobs 44, as best shown in FIG. 3A. U-shaped end48 defines a space that is larger than knob 44, so that when ON segment14 of switch 12 is pushed, the lower part of U-shaped end 48 lifts knob44 and module interface port 18 in the direction of arrow 50 to movemodule interface port 18 and tube 40 toward cartridge valve 26 to openit. As switch 12 returns to its rest position due to the action ofspring arms 52 against a hard surface on the fuel cell system (notshown), the extra space between the arms in U-shaped end 48 allowsswitch 12 to return to its neutral or rest position without retractingmodule interface port 18. This allows module interface port 18 to remainengaged to keep cartridge valve 26 open.

In some embodiments, module interface port 18 does not contain ashut-off valve and cartridge shut-off valve 26 is used as the fluidicshut-off valve for fuel cell system 21. Advantages of omitting ashut-off valve on module 10 include obviating the wear and tear of sucha valve, which is used repeatedly, and minimizing the probability offailure of such valve. The advantages of relying on the cartridgeshut-off valve 26 include that a fresh new valve is provided with eachnew cartridge. In other embodiments, module interface port 18 mayinclude a shut-off valve. Such a shut-off valve may be used to preventingress of air or other materials into the system when a cartridge isnot inserted, or may be used to enable system-controlled shut-offsequences.

From a neutral or rest position shown in FIG. 3B, yokes 46 aresubstantially parallel to module 10. In one embodiment, switch 12 haspivot boss 54 that allows switch 12 to pivot or rotate. As ON segment 14is pushed in direction 56, yokes 46 are rotated in direction 58. Thismovement moves module interface port 18 in direction 50 to an engagedposition shown in FIG. 3C, as discussed above.

Module interface port 18 further comprises a mechanical detent 45 thatcooperates with another mechanical feature in module 10 to keep moduleinterface port 18 in the engaged position shown in FIG. 3C after switch12 has returned to its neutral position. Module interface port 18further comprises leg 47 that protrudes through module 10 to actuate anelectrical switch on a printed circuit board (PCB) that contains thefuel cell circuit whenever module interface port 18 is in the engagedposition shown in FIG. 3C.

This sequence of operation of module interface port 18 is furtherillustrated in FIGS. 4A-4D. Module 10 shown in FIG. 4A is in the OFFstate with module interface port 18 refracted with spring arms 52maintaining switch 12 in its neutral position. A user moves ON segment14 of switch 12 in direction 56 which rotates yokes 46 about pivot boss54 in direction 58 and extends module interface port 18 in direction 50to turn module 10 to the operating or ON position. Extending moduleinterface port 18, as discussed above, opens shut-off valve 26 ofcartridge 20 to commence fuel flow from the cartridge through module 10to fuel cell system 21. As the user releases switch 12, spring arms 52pushes against a hard surface on the fuel cell system (not shown) tomove switch 12 and yoke 46 back in opposite direction 56′ and direction58′, respectively, as shown in FIG. 4C. Module interface port 18 remainsextended and the top of U-shaped end 48 of yoke 46 rests on knob 44 ofmodule interface port 18. Module 10 should remain in the configurationshown in FIG. 4C while the fuel cell system is operating. To turn thefuel cell system OFF, the user moves OFF segment 16 of switch 12 indirection 56. This rotates yoke 46 in direction 58′ to move knob 44 andmodule interface port 18 in direction 50′ to retract module interfaceport 18 to return shut-off valve 26 in cartridge 20 to the closedposition, as shown in FIG. 4D. As the user releases switch 12, module 10returns to the configuration of FIG. 4A.

It is noted that in the configurations of FIG. 4B or FIG. 4D, a purgevalve may be activated or armed at substantially the same time as ONsegment 14 or OFF segment 16 of switch 12 is activated to purge theanode side of the fuel cells. The operations and structures of module10's purge valve are discussed below. Also as module interface port 18is extended as shown in FIG. 4B the fuel cell circuit is activated orturned ON, and as module interface port 18 is retracted as shown in FIG.4D the fuel cell circuit is de-activated or turned OFF.

In another embodiment, module interface port 18 has its own shut-offvalve that obviates the need for the module interface port 18 to advancetoward and retract from the fuel cartridge. Once cartridge 20 isinserted, its own shut-off valve 26 remains open and the flow of fuelgas is controlled by the shut-off vale of the module interface port.This shut-off valve may be a passive mechanical valve, or it may be anelectromechanical gas shut-off valve that can be controlled by thecontroller.

After the fuel, e.g., hydrogen gas, enters module 10 through moduleinterface port 18, the fuel's pressure is modulated by pressureregulator 60. As best shown in FIGS. 1C and 5, fuel enters through innertube 30 and reaches top side 22 of module 10, where the fuel flows tothe inlet side or high pressure side of pressure regulator 60. Asuitable pressure regulator comprises inlet diaphragm or high pressurediaphragm 62, shuttle 64, outlet diaphragm or low pressure diaphragm 66.Shuttle 64 has larger end 68 in contact with outlet diaphragm 66 andsmaller end 70 in contact with inlet diaphragm 62, and is housed inshuttle housing 72. Spring 74 is located inside pressure regulator 60and is positioned between large end 68 of shuttle 64 and inlet diaphragm62. The spring force of spring 74 and the resiliency of diaphragms 62and 66, as well as the pressure in outlet chamber 76, determine theopening pressure or cracking pressure of pressure regulator 60. Inletchamber 78 is located between inlet diaphragm 62 and a portion of topside 22 of module 10. Preferably, shuttle housing 72 is in fluidcommunication with a reference pressure. In one example, shuttle housing72 is provided with at least one vent 73 to access atmospheric pressure.

The operations of suitable pressure regulators with movable shuttles arewell described in commonly owned patents and patent applications,including U.S. Pat. No. 8,002,853 and published patent applications US2010/0104481, US 2011/0189574 and 2011/0212374, and commonly ownedpatent application entitled ‘Fluidic Components Suitable for Fuel CellSystems Including Pressure Regulators and Valves” and filed on even dateherewith. The references are incorporated herein by reference in theirentireties. Other types of suitable pressure regulators include but arenot limited to those described in published patent applications US2008/0233446 and WO 2011/127608. Any pressure regulator described inthese references can be used with module 10. These references areincorporated herein by reference in their entireties.

Referring to FIG. 1C, fuel enters through tube 30 to reach top side 22of module 10. At the terminal end 30′ of tube 30, as best shown in FIG.6A, fuel is directed to inlet channel 80 and flows in direction 82 toinlet 84 of pressure regulator 60. If the outlet pressure in outletchamber 76 and the pressure exerted by spring 74 and diaphragms 62 and66 are below the opening pressure of regulator 60, inlet diaphragm 62flexes toward outlet diaphragm 66 and incoming fuel enters inlet 84 intoinlet chamber 78, where it expands and undergoes a pressure drop due tothe expansion.

After expanding and dropping pressure, the fuel exits pressure regulator60 at outlet 86, as best shown in FIG. 6A, flows through outlet channels88 in directions 90 and out of module 10 at module outlet 92 to the fuelcell(s) illustrated in FIG. 7, discussed below, and fuel cell system 21.Although two outlet channels 88 are shown, any number of outlets can beutilized.

A pressure feedback structure is also provided to lead the outletpressure and/or pressure in the fuel cells back to outlet diaphragm 66,so that pressure regulator 60 may close, i.e., shuttle 64 pushes inletdiaphragm 62 toward inlet 80 to stop the flow of fuel through thepressure regulator until the outlet pressure or fuel cell pressuredecreases. A feedback port 94 is provided on outlet channel 88, shown inFIG. 6A. Port 94 is connected to first feedback channel 96 in direction98 and along second feedback channel 100 along direction 102 to outletchamber port 104, where the fuel outlet pressure can be sensed by outletdiaphragm 66, as best shown in FIG. 6B. It is noted that the pressurefeedback structure has no dedicated exit, i.e., it is a blind hole, suchthat feedback flow directions 98 and 102 can be reserved depending onthe flexing states of diaphragms 62 and 66.

Additionally, the flow channels shown in FIGS. 6A and 6B can be coveredby a thin layer to create closed flow channels to keep the fuel fromexiting the channels. These thin covers can be thin adhesive films madefrom materials that are inert to fuel cell fuels, such as hydrogen,oxygen or methanol. Such thin covering films are shown as element 106 inFIGS. 1C, 3A-C, 4A-D, 5A, et seq., and can also be used to cover purgechannels, described below.

In an alternative embodiment, coil spring 74, which is generally madefrom a metal or a metal alloy, is replaced by a molded feature such as aspring arm similar to spring arm 52 on switch 12. This molded featuremay be constructed of metal or metal alloys, or may be constructed ofplastics or other materials with suitable mechanical properties.Additionally, instead of providing inlet 84 and outlet 86 to pressureregulator 60 that are connected by a bypass channel, an internal channelthrough diaphragms 62 and 66 and shuttle 64 to connect outlet chamber 76to inlet chamber 78. This bypass channel is spaced apart from shuttle 64and diaphragms 62 and 66 and connects outlet chamber 76 to inlet chamber78. Pressure regulators with an internal channel through the diaphragmsand shuttle are fully disclosed in commonly owned PCT publication No. WO20] 3/093646, more specifically in FIGS. 8A-D of said PCT publication.WO 2013/093646 is incorporated herein by reference in its entirety.

Integrated fluidic interface module 10 also comprises a purge system orpurge valve (hereinafter designated with reference number 109 or 109′)to remove residual gas from the anode plenum in the fuel cells. Anexemplary fuel cell 108 is illustrated in FIG. 7, which showsside-by-side planar PEM fuel cells disclosed in commonly owned publishedinternational application WO 2011/079377. Other suitable fuel cells,including planar and stacked fuel cells, are discussed below. Residualgases including byproducts, inert gases and water vapors can collect onthe anode side 107 of fuel cell 108. It is desirable to purge theseresidual gases from anode 107 periodically, or at system start up or atsystem shut-down using fuel, such as hydrogen gas, from fuel cartridge20. Purging the fuel cells or the fuel cell system is venting the anodeplenum. In one embodiment, when a purge valve is opened fuel entersmodule 10 flowing through pressure regulator 60 and out of module outlet92 to anode 107 of fuel cell 108. The fuel gas pushes the residual orinert gas from the anode back to module 10 and through the purge valveand out to vent.

One embodiment of the purge valve system, described below andillustrated in FIGS. 8A-10B, purge valve 109 is manually activated by auser preferably to start the fuel cell system, e.g., by pushing ONsegment 14 of switch 12. Purge valve 109 remains ON or opened when theswitch returns to its neutral or rest position. In other words, theclosing of the purge valve is not connected to switch 12. Instead, purgevalve 109 is closed or moved to the OFF position when the fuel cellreaches a steady level after a start-up conditioning process to produceelectricity. The conditioning process is a start-up process, where fuelcells heat and humidify themselves. The electricity from the fuel cellis conducted through a resistive load, which heats up the resistiveload. When heated to a predetermined level, the resistive load such as ashape memory alloy changes its shape or contracts back to a shape thatit remembers and closes the purge valve or moves it to the OFF position.The resistive load may include a SMA and other resistive elements, whichmay preferentially located to speed up the warming process. Thisinventive purge valve system is therefore manually or mechanicallyactuated and electrically and/or thermally de-actuated. In other words,purge valve 109 is a semi-automatic purge valve. The present inventionrelies on the fuel cell's ability to produce enough power to actuate theresistive load/shape memory alloy load to close the purge valve. Thepresent invention does not rely on sensors or control systems to detectwhether the anode is filled with hydrogen. The present invention usesthe fuel cell both as a hydrogen gas sensor and as a power source toclose the purge valve.

The inventive purge system 109 in module 10 comprises at least a purgeshuttle 110 that cooperates with a sealing member 112, such as an 0-ringor a sealing disk, as shown in FIGS. 1C, 8A-8D and 10A-10B. As bestshown in FIGS. 9A-9C, shuttle 110 comprises a sealing portion 114, anopen portion 116, a shoulder 118 and an optional extension 120. Openportion 116 contains a cut-out or an open notch 122, which is a cut-outthat lets residual gases through to exit. In a closed configuration asshown in FIG. 10B, sealing portion 114 of purge shuttle 110 ispositioned next to sealing member 112. In an open configuration to ventgases shown in FIG. 10A, open portion 116 and notch 122 are positionednext to sealing member 112 to create a flow path through notch 122 andpurge shuttle to vent residual gas.

Referring to FIG. 10B, the compressive force exerted by compressedsealing member 112 on sealing portion 114 of purge shuttle 110 is indirection 113, and the actuation force that moves shuttle 110 from theclosed configuration of FIG. 10B to the open configuration of FIG. 10Ais in direction 115. Directions 113 and 115 are substantiallyperpendicular to each other. The diameters of sealing portion 114 andopen portion 116 are substantially the same, and these diameters arelarger than the inner diameter of sealing member 112, so that sealingmember 112 is compressed and exerts a force in direction 113. There isno other axial or longitudinal force other than friction or no biasingforce from a spring that acts on purge shuttle 110 when it moves,thereby enabling purge shuttle 110 to remain in the closed position andto remain in the open position, once purge shuttle 110 is so moved.

Referring to FIG. 8A, purge shuttle 110 is supported on a wire 124 thatis suspended on two posts 126, which are anchored on the body of module10. Module 10 has a channel 127 that is sized and dimensioned to storewire 124. Wire 124 is inserted under shoulder 118 of purge shuttle 110.As best shown in FIG. 9B, purge shuttle 110 has a slit 128 which opensto channel 130. Slit 128 is sized and dimensioned to allow wire 124 toslip through and be loosely held within channel 130. In one embodiment,wire 124 is made from or comprises a material that reverts to anoriginal shape when heated to a predetermined temperature. A suitablematerial for wire 124 is a shape memory alloy (SMA). SMA materials areelectrically conductive and electrically resistive, such that when anelectrical current, e.g., from fuel cell 108, flows through it thecurrent also heats the SMA wire. Suitable SMA materials include, but arenot limited to, nickel-titanium or nitinol, which is commerciallyavailable as Flexinol™. Other suitable SMA materials include the alloysof Ag—Cd, Au—Cd, Cu—Al—Ni, Cu—Sn, Cu—Zn, Cu—Zn—X (X=Si, Al, Sn), Fe—Pt,Mn—Cu, Fe—Mn—Si, Pt alloys, Co—Ni—Al, Co—Ni—Ga, Ni—Fe—Ga, Ti—Pd invarious concentrations, Ni—Ti—Nb and Ni—Mn—Ga. Wire 124 forms a part ofpurge valve 109.

In this embodiment, when the user activates ON segment 14 of switch 12,the user also opens the purge valve. Switch 12, as best shown in FIG.8B, in addition to yokes 46 also has purge valve pusher 132, whichterminates in two fingers 134. Fingers 134 push down on shoulder 118 ofpurge shuttle 110 in direction 58, discussed above. This motion movespurge shuttle 110 to the open configuration of FIG. 10A: Extension 120of purge shuttle 110 disconnects the external load (e.g., an electronicdevice) from the fuel cell and connects wire 124 to the fuel cell. Asthe residual gases are purged from anode 107 and replaced by hydrogenfuel, fuel cell 108 produces more electricity, which conducts throughwire 124 and heats the wire. As the fuel cell production reaches adesired or steady state level indicating that the purge process iscomplete, wire 124 is sufficiently heated to return to its memorizedshape, i.e., it contracts its length to pull purge shuttle back to itsclosed configuration as shown in FIG. 10B. Once the purge shuttle isback to the closed configuration, wire 124 is disconnected from the fuelcell circuit, and the external load is reconnected to the fuel cell.Wire 124 is allowed to cool and return to its longer length.

As shown in FIG. 10C, PC board 135 which contains the electricalcircuitry, among other things, is disposed adjacent to side 22 ofinterface module 10. PC board 135 preferably has an electrical outputport 137, such as a USB port, to conduct the electricity generated bythe fuel cells 108 to an external load or electronic device. Externalload includes, but is not limited to, DC-DC converter, powerconditioning elements, electrical regulator and other electricalcomponents necessary to provide regulated power to the electronicdevice.

Referring to FIGS. 8C-8E, residual gases to be purged flow in direction136 enter module 10 through purge port 138. Inside module 10, theresidual gases flow through purge channel 140 along direction 142 andexit module 10 via notch 122 of open portion 116 on purge shuttle 110along direction 142, as shown in FIG. 8D. Residual gases include inertgases, water vapors and condensed water that migrate into the anodeplenum through the polymer exchange membrane (PEM) when the fuel cellsystem is inactive and through the fuel conduits when no fuel cartridgeis connected to the system.

Hence, purge valve system 109 of the present invention is manuallyactivated when the fuel cell system is turned on by the user by pushingswitch 12 and is automatically deactivated when the fuel cell issufficiently purged. The fuel cell itself determines when the anodechamber(s) is sufficiently purged, which coincides with the productionof electricity when hydrogen gas replaces the residual gases. Thede-activation process itself, which occurs automatically, preferablydoes not consume electricity after the fuel cell is fully conditioned.The power produced by the fuel cell during this transient conditioningperiod, which is not useful to power a device, is used to heat up wire124. The power produced during the conditioning period can also be usedto heat other components in the fuel cell system 21. No usefulelectricity needs to be used to de-activate purge valve system 109.

The length and width of wire 124 can be readily ascertained with thesteady state output and/or the output during the conditioning of thefuel cell, the thermal conductivity and thermal capacitance of the SMAmaterial, the temperature at which the SMA material reverts to itsmemorized shape, the amount of retraction by the SMA material, and theforce necessary to move purge shuttle from the closed configuration tothe open configuration. These factors can be readily look up ormeasured.

An advantage of this purge valve system is that if the fuel cell isinsufficiently purged the valve remains open until the purge process iscomplete and fuel such as hydrogen gas is reacted in the fuel cell toproduce electricity.

The advantages of semi-automatic purge valve 109 over conventional purgevalves are readily apparent. Manually operated purge valves may bepurged too short which leaves residual gases in the fuel cell, or toolong which wastes fuel gas. Elapsed or timed purge valves suffer thesame disadvantages as manually purged valves, and they require extracomponents for the timing mechanism. Electronically actuated purgevalves require power from the fuel cells operating in steady state, andextra parts such as solenoid valves and sensors. Electronically actuatedvalves also cannot be operated at start-up due to the lack of steadystate power, or cannot work without an independent power source, such asbatteries. Electronically actuated valves also need a microprocessor orcontroller to function. The deficiencies of conventional purge valvesare remedied by the purge valve 109 described above and shown in FIGS.8A-10B, and inverse purge valve 109′ described below.

In another embodiment, this purge valve with SMA wire 124, purge shuttle110 and sealing member 112 can be deployed as a safety shut-off for alarge number of applications to shut off any system when the systemtemperature, which triggers the SMA wire, reaches a certainpredetermined level. Purge shuttle 110 can act like an electrical switchthat opens a circuit when the SMA wire retracts. A manual reset, bymanually pushing the purge shuttle, is necessary to close the circuit torestart the system.

This safety shut-off feature can be applied to shut down a fuel cellsystem when it is idle. When there is no load on the fuel cell, e.g.,when no electronic device is connected to a fuel cell charger, theelectrical current can be diverted to purge valve 109 to heat SMA wire124 to retract and turn the fuel cell off. In one example, an SMA wirecan be connected to module interface port 18. If the fuel cell systemoverheats, then the SMA wire retracts in direction 50′ to withdraw tube30 from shut-off valve 26 to turn the system off. This action is theequivalent of shutting down the system without pushing OFF segment 16 ofswitch 12. In another example, a simple circuit is connected between SMAwire 124 of the purge valve 109 or 109′ and USB port 137. A temperaturesensor, such as a thermistor, connected to a gate is positioned on thiscircuit. When a threshold temperature is reached the gate opens toisolate the USB port from the fuel cell circuit and connects thiscircuit to SMA wire 124 to retract the wire to close the system. Inanother example, the material of SMA wire 124 is selected to retract ator proximate to the system shut-off temperature to shut the system downautomatically when the system temperature reaches the shut-offtemperature. In another example, a processor or micro-processorpreferably located on PCB board 135 directs electrical current to SMAwire 124 after a pre-determined period of inactivity.

In another embodiment, the purge shuttle may have two open portions 116and 116′, as best shown in FIG. 11, and designated as double-ended purgeshuttle 144. Double-ended purge shuttle 144 can be used as a fluidcontrol in a manifold. For example, one SMA wire 124 can be positionedin channel 130 below shoulder 118 and a second SMA wire 124 can bepositioned above shoulder 118. The fuel cell or another electricalsystem or a controller can selective activate one specific wire 124 tomove purge double-ended shuttle 144 to first open section 116 and activethe other wire 124 to move double-ended purge shuttle 144 to the otheropen section 116′. A third SMA wire 124 of different length can bepositioned either above or below shoulder 118 to move double-ended purgeshuttle 144 to sealing portion 114. By varying the position ofdouble-ended purge shuttle 144, a specific flow channel in a manifoldcan be selected.

In another embodiment, purge valve 109′ operates in an inverse manner.Inverse purge valve 109′ is armed or opened when the fuel cell system isturned OFF. In this configuration, when the fuel cell system is OFFinverse purge valve 109′ is open, the fuel cell system is ready to bepurged when the fuel cell system is turned ON again. Similar to theembodiment discussed above, the fuel cell closes inverse purge valve109′ with the electricity it produces. A minor adjustment to switch 12is made to accomplish this sequence. Referring to FIG. 8B, purge valvepusher 132, which is shown to be associated with the ON segment 14 ofswitch 12, can be relocated and be attached to the OFF segment 16 ofswitch 12, so that actuation of OFF segment 16 would move inverse purgevalve to the ON configuration. Alternatively, switch 12 and purge valvepusher 132 may remain substantially the same as shown in FIG. 8B andpurge shuttle 110 is modified as shown in FIG. 13 to be an inverse purgeshuttle 110′ with open portion 116 located at one end and sealingportion 114 away from the end. Additionally, shoulder 118 of the purgeshuttle is relocated to be on the opposite side of purge valve pusher132. As shown in FIG. 10D, as OFF segment 16 is pushed in direction 56moving purge valve pusher 132 in direction 58′, purge valve pusher 132moves purge shuttle 110′ in direction 50′ to align open portion 116 withthe seal 112 to open and arm inverse purge valve 109′ to vent the nexttime the system is turned ON.

One advantage of inverse purge valve 109′ is that the valve would notpurge even if a user repeatedly presses ON segment 14 of switch 12,while the fuel cell system is in operation, or holding ON segment 14down for an extended time, since inverse purge valve 109′ is decoupledfrom ON segment 14. Purging the system while the fuel cell is in fulloperation would waste fuel, disrupt the operation of the fuel cell,damage SMA wire 12 and cause other adverse effects.

Another advantage of inverse purge valve 109′ is that while the fuelcell system is running, a purge operation cannot occur to preventover-purging. The user would first turn the system OFF by actuating OFFsegment 16, which turns the entire system OFF and open the purge valve,and then the user would actuate ON segment 14 to turn the fuel cellsystem back ON and to purge the system.

Another advantage of the inverse purge valve 109′ is that when the fuelcell system is shut down and with inverse purge valve 109′ in the openconfiguration, the anode and the rest of the fuel cell systemdepressurize and reach equilibrium with the ambient environment. Thismay reduce the amount of water condensation within the fuel cell systemas the fuel cell cools, thereby lessening the purge duration on the nextstartup.

In yet another embodiment, purge valve pusher 132 is connected to moduleinterface port 146 as shown in FIG. 12, which is moved by switch 12 toan extended position in direction 50 to connect to cartridge 20 or to aretracted position in direction 50′ to disconnect from cartridge 20 asdiscussed above. As module interface port 146 is moved in direction 50,which has the same motions as module interface port 18 shown in FIGS.3B-3C, purge valve pusher 132 would push purge shuttle 110 in direction50. In this embodiment pusher 132 would be positioned on surface 148 ofshoulder 118, as illustrated in FIG. 9B. This would position notch 122and open portion 116 opposite of sealing member 112 thereby turning thepurge valve 109 to the open configuration.

A modification to the purge shuttle allows the purge system in thepreceding paragraph to operate in the inverse manner, i.e., turning thesystem off would open the purge valve. As shown in FIG. 13, purgeshuttle 110′ is similar to purge shuttle 110 except that the locationsof sealing portion 114 and open portion 116 of the shuttle are switched.When module interface port 146 retracts as the system shuts down orturning OFF, purge valve pusher 132, which is attached to moduleinterface port 146 and is in contact with surface 150 of shoulder 118,moves in direction 50′ to position open portion 116 and notch 122opposite of sealing member 112 to open the purge valve.

It is noted that in the embodiments where purge valve pusher 132 isattached to module interface port 146, pusher 132 is positioned atsurface 148 or 150 of shoulder 118, so that module interface port 146can only manually move the purge shuttle 110, 110′ in one direction 50or 50′. SMA wire 124 is located on the opposite surface to automaticallyclose the purge valve.

The purge system using module interface port 146 and purge shuttle 110′in the inverse manner confers a number of advantages, including thesituation where every time a new cartridge 20 is inserted into the fuelcell system, inverse purge valve 109′ is moved to or remains in the openconfiguration and the fuel cell system is ready to be purged. When anold or empty cartridge 20 is removed and switch 12 is turned OFF, thenmodule interface port 146 is retracted and purge valve 109′ with purgeshuttle 110′ is in the open configuration and the fuel cell system isready to be purged when a fresh cartridge is inserted and switch 12 isturned ON.

However when the old or empty cartridge 20 is removed and switch 12remains in the ON position, module interface port 146 remains extendedand purge valve 109′ remains in the closed configuration.Advantageously, when a fresh cartridge is inserted the cartridge due tofriction and contacts with module interface port 146, the insertionmotion pushes module interface port 146 to the retracted position andpurge valve 109′ is in the open configuration and the fuel cell systemis ready to be purged at the next start up.

Hence, the purge system using module interface port 146 and purgeshuttle 110′ operating in the inverse manner assures that when a freshcartridge is used for the first time the fuel cell system is ready to bepurged at the next start up, as well as after turning the fuel cellsystem OFF and then ON again.

Another purge valve 200 is illustrated in FIGS. 18A-F. Similar to purgevalves 109 and 109′ described above, purge valve 200 also comprises SMAwire 124. In this embodiment, SMA wire 124 is stretched by apre-stressed cantilever beam in the OFF position and in the ON positionand has substantially the same longer length in both the OFF and ONpositions. The purge valve 200 is maintained in the ON position by alatch mechanism, and is spring loaded so that the valve returns to theOFF position unless it is held in the ON position by the latch mechanismor contraction by the SMA wire. To move valve 200 from the ON positionto the OFF position, SMA wire 124 is temporarily heated by the fuel cell108 as the anode 107 is purged and hydrogen fuel gas fills the anodesufficiently to allow the fuel cell 108 to generate sufficient currentto heat and shrink SMA wire 124. As SMA wire 124 shrinks, it pulls onthe cantilever beam and releases the latch mechanism and thepre-stressed cantilever beam returns to the OFF position and stretchesSMA wire 124 when the heating stops. Hence, purge valve 200 is anothersemi-automatic valve that may be opened manually, preferably when a userpushes an ON button and unlike valve 109 and 109′ held in the ONposition by a spring-loaded latch mechanism and in the OFF position by apre-stressed cantilever beam, and is automatically closed by theelectrical current generated by the fuel cell. Advantageously, purgevalve 200 may also be intermittently opened as necessary after the userpushes the ON button during the operation of the fuel cell system for aslong as desired by applying a temporary current to the SMA wire.Elements that are similar between purge valves 109/109′ and 200 mayshare the same reference numbers.

FIGS. 18A-C show a sequence of purge valve 200 from the OFF position tothe ON position and the released position, respectively. FIGS. 18D-Fshow the same sequence but using cross-sectional views along thelongitudinal axis of valve 200.

Referring to FIGS. 18A and 18D which shows purge valve 200 in the OFF orclosed position, valve 200 has inlet 138 where the gas to be purgedflows into purge valve 200 in direction 136 and out of outlet 202 inexiting direction 142. Flow directions 136 and 142 of the gas to bepurged and the purge inlet 138 are shown in FIGS. 18D and 18E. Purgevalve 200 also has SMA wire 124, which is anchored to the valve body atend 204. SMA wire 124 wraps around free end 206 of cantilever beam 208.Free end 206 has a shoulder 210 that retains SMA wire 124 in place.Cantilever beam is pre-stressed such that free end 206 is biaseddownward onto the raised ridge or lip of inlet 138 to close the valve.Purge valve 200 also has a movable biased slider 212, which has mainbody 214 and forked legs 216 with hooked ends 218. Forked legs 216 forma spring and store energy when legs 216 are pressed toward each other,as discussed further below.

Slider 212 is biased toward the OFF position shown in FIGS. 18A and 18Dby one or more springs. A helical spring 220 can be positioned betweenledge 222 on the valve body and main body 214 of slider 212 to pushslider 212 toward the OPEN position. Additionally, spring arms 224 canalso be positioned on main body 214, as shown, that can flex to storepotential energy when slider 212 is moved to the ON position, as bestshown in FIGS. 18B and 18E. Additionally, the valve body may also havespring arms 226, which can flex to store energy when slider 212 is movedto the ON position.

Purge valve 200 further comprises a flexible diaphragm 228 fluidicallydisposed between inlet 138 and outlet 202. In the OFF position,extension 230 of free end 206 pushes diaphragm 228 toward the raisedridge on inlet 138 to close inlet 138 preventing the gas to be purgedfrom flowing through valve 200. Diaphragm 228 preferably is made from anelastomeric material that can seal inlet 138, and in its relaxed orun-stretched state is sized and dimensioned to form a space 240 or flowpath above the raised ridge on inlet 138 connecting inlet 138 and outlet202, as best shown in FIG. 18D. Extension 230 preferably has a largerdiameter than inlet 138, and due to the downward extending force fromthe pre-stressed cantilever beam 208 extension 230 presses diaphragm 228against the raised ridge of inlet 138 to seal the inlet.

To maintain valve 200 and slider 212 in the OFF position, the valve bodyhas notches 232 defined thereon and notches are sized and dimensioned toreceive hooked ends 218 of forked legs 216 of slider 212, as best shownin FIGS. 8A and 8D. Due to the spring-like property of forked legs 216,hooked ends 218 are retained in notches 232 and slider 212 and valve 200are held in the OFF position.

To open valve 200 to purge the anode side of fuel cells 108, a userpushes an ON button mechanically attached to slider 212 in direction234, as shown in FIGS. 18B and 18E, compressing coil spring 220 andflexing spring arms 224, 226. Although shown in FIGS. 18B, 18C, 18D and18F as overlapping, spring arms 224 and 226 do not overlap each other,but are flexed or displaced by a combined amount substantially equal tothe overlapping amount shown. It is noted that only one set of springarms 224 or 226 may flex. Activation of the ON button or pushing slider212 in direction 234 also pushes hooked ends 218 away from notches 232due to first ramp 236 on the distal ends of forked legs 216 toward end204. This movement also engages slider 212 to cantilever beam 208. Freeend 206 and its shoulder 210 rides over second ramps 238 until shoulder210 catches second ramps 238, as best shown in FIGS. 18B and 18D, andslider 212 is retained in or latched to the ON position. Hence, shoulder210 and second ramps 238 for the latching mechanism that retains slider212 or valve 200 to the ON position. The movement from the OFF position(FIG. 18A) to the ON position (FIG. 18B) does not significantly alterthe length of SMA wire 124.

Also, in the ON position free end 206 is lifted upward by second ramps238 and moves extension 230 of free end 206 away from the raised ridgeof inlet 138. The flexibility or spring-like property of diaphragm 228is designed such that when extension 230 moves away from the raisedridge of inlet 138, the gas to be purged enters space 240 located belowdiaphragm 228 and exits valve 200 through outlet 202 in direction 142.It is noted that diaphragm 228 is sealed around its periphery 242 asshown in FIGS. 18D-F to ensure that the gas to be purged has one ingressat 138 and one egress at 142.

As discussed above, in the ON position wire 124 is connected to the fuelcell and is heated by the fuel cell as hydrogen gas fills the anode sideindicating a completion of the purge, and wire 124 contracts to itsmemorized shorter length. As best shown in FIGS. 18C and 18F, theshortened SMA wire 124 pulls free end 206 upward disengaging shoulder210 from second ramps 238 thereby releasing slider 212. Spring 220and/or spring arms 224 and/or 226 push slider 212 away from end 204 toreturn to the OFF position shown in FIGS. 18A and 18D. This upwardmovement also disengages SMA wire 124 from the fuel cell, and as SMAwire 124 cools and/or relaxes, as described above, pre-stressedcantilever beam 208 returns to its OFF position and stretches SMA wire124. Extension 230 of cantilever beam 208 again presses diaphragm 228toward the raised ridge on inlet 138 to close valve 200.

One advantage of valve 200 is that SMA wire 124 is isolated from theflow of the gas to be purged by diaphragm 228. This separation shieldsSMA wire 124, which is made from a metal alloy discussed above, from theflow of the gas to be purged. In purge valves 109 and 109′ the gas to bepurged flow through notch 122 of purge shuttle 110 and SMA wire 124 isexposed to this gas and heat can transfer from wire 124 to the gas to bepurged. This heat transfer may affect the rate of change of SMA wire 124depending on the size and the compositional make-up of the alloy. Thismay cool SMA wire prematurely. In purge valve 200, SMA wire 124 isisolated from the gas to be purged by diaphragm 228 thereby minimizingor obviating this issue.

Another advantage of purge valve 200 is that it can be openedintermittently to purge the fuel cell during operation. As discussedabove, in the OFF position (FIGS. 18A and 18D) SMA wire is stretched bythe pre-stressed cantilever beam 208. If the fuel cell system sends acurrent to SMA wire 124 while it is in the OFF position it would shrinkand pulls free end 206 of cantilever beam 208 upward similar to that inthe released position illustrated in FIGS. 18C and 18F. This liftsextension 230 of free end 206 and diaphragm 228 from the raised ridge oninlet 138 to open the purge valve. To close the purge valve, theelectrical current stops and SMA wire 124 cools and is stretched bypre-stressed cantilever as it returns to the OFF position.

Hence, in the user activated mode at system start-up one sequence ofoperation for purge valve 200 is as follows: (i) OFF position to ONposition caused by a user pressing a start button, (ii) ON position toRELEASE position caused by the current from the fuel cell as the purgingprocess is completed heating the SMA wire and shortening it (iii)RELEASE position to OFF position caused by the cessation of currentthrough the SMA wire controlled by the return of slider 212 to its OFFposition and/or by a control system in the fuel cell system reading theposition of the slider.

During the normal operation of the fuel cell system, intermittentpurging has the following sequence: (i) OFF position (FIG. 18A) toRELEASE position (FIG. 18C, except that there is no movement by slider212) caused by a temporary flow of current through the SMA wire to purgeand (ii) said RELEASE position to OFF position caused by a cessation ofcurrent through the SMA wire by the control system in the fuel cellsystem.

Another purge valve 200′ is illustrated in FIGS. 19A-D. Valve 200′ issimilar to valve 200, except that cantilever beam 208 is pre-stressed tobias upward or away from the inlet 138 (or outlet 202) and slider 212moves in one direction to press free end 206 downward or toward inlet138 to close valve 200′. Slider 212 moves in the opposite direction toallow free end 206 of cantilever beam 208 to move upward or away frominlet 138 to open valve 200′. Slider 212 is still spring biased byspring 220 to the OFF or closed position and a latch mechanism hold theslider 212 in the ON or open position until SMA wire 124 is heated andshrunk to release the latch mechanism.

Referring to FIGS. 19A and 19C, which show purge valve 200′ in the OFFposition, end 213 of slider 212 is holding terminal end 209 ofcantilever beam 208 downward toward inlet 138 against the biasingtendency of cantilever beam 208 to move upward. Extension 230 of freeend 206 presses diaphragm 228 to seal the raised edge of inlet 138 toclose valve 200′. FIGS. 19B and 19D show purge valve 200′ in the ONposition. Slider 212 moves in the direction shown, e.g., when an ON/OFFpush button is pushed, and terminal end 209 of cantilever beam 208 movesupward due to the biasing tendency of the cantilever beam until terminalend 209 catches end 213 of slider 212 as shown. This forms a latchingmechanism holding slider 212 to cantilever beam 208. In thisconfiguration, extension 230 also moves upward away from inlet 138 toopen valve 200′ to the ON position. SMA wire 124 is also anchored to thehousing of the valve and is wrapped around terminal end 209 ofcantilever beam 208. When heated by the fuel cell, SMA wire 124 shrinksand pulls terminal end 209 away from end 213 of slider 212 to releasethe latch. Slider 212 biased by spring 220 or the spring arms 224 or 226(not shown in FIGS. 19A-D) moves back to the OFF position.

It is further noted cantilever beam 208 and its extension member 230 canalso close valve 200 and 200′ by closing outlet 202 instead of closinginlet 138 discussed above.

It is noted that purge valve 200 can perform any function that purgevalves 109 and 109′ can perform. For example, valve 200 can be in the ONposition when the fuel cell system 21 is turned ON or is turned OFF. Asecond valve 200 can also be included in integrated fluidic interfacemodule to automatically turn off fuel cell system 21 if no electricalcurrent is drawn from the system, e.g., when system 21 is idle. Secondvalve 200 would be in fluidic connection with terminal end 30′ of innertube 30 of port 18. The inlet of second valve 200 would be connected toterminal end 30′ and the outlet of second valve 200 would be the newterminal end 30′ that is in fluid communication with pressure regulator60, as best illustrated by FIG. 1C. FIG. 18F is also labeled withterminal end 30′. Second valve 200 can also be located elsewhere in thefluidic circuit. For example, the inlet could be connected to thedownstream side of pressure regulator 60 and the outlet could be outlet92 that connects to the fuel cell.

The second valve 200 can be turned to the ON position by the same motionor the same push button that turns the first purge valve 200 to the ONposition, so that the user only has to perform one operation. After thepurging step the fuel cell heats the first purge valve 200 to close it,but the second valve 200 remains open. A circuit or chip on board 135 isprovided to ascertain whether fuel cell system 21 is idle or if nodevice is drawing or withdrawing current from fuel cell system 21, thenthis circuit can send current to SMA wire 124 of the second valve tomove it to the OFF position to cut off fuel and shut down fuel cellsystem 21. This is done automatically without user's input.

Accordingly, another aspect of the present invention includes a methodof operating a fuel cell system comprising at least one fuel cell and anautomatic shut-off valve (200). This method comprising the steps of

(a) opening the automatic shut-off valve (200);

(b) flowing fuel to the fuel cell system to produce an electricalcurrent;

(c) monitoring the electrical current produced by the fuel cell andtransmitted to a consumer device, and

(d) when said electrical current is reduced to a predeterminedthreshold, connecting the at least one fuel cell to a conductive elementin the automatic shut-off valve to close said shut-off valve.

The conductive element can be a shape memory alloy (SMA) and in step (d)the fuel cell heats up the conductive element which retracts and movesthe shut-off valve to a closed position.

The ON button that the user activates when purge valve(s) 200 is usedwould be simpler because only slider(s) 212 has to be moved in onedirection. Additionally, the initial activation of the ON button can beeliminated if the act of inserting cartridge 20 into system 21 alsomoves slider(s) 212 to the ON position. When the second valve 200 isused, fuel cell system 21 can automatically turns itself off fornon-use, the user only has to activate the ON button for subsequentuses.

The present invention further includes methods for operating the fuelcell system using the purge valves 109 and 109′ described above or otherpurge valves. First, method 152 is shown in FIG. 14. Demonstrating theintegrated aspect of the present invention, a user activates the systemonce at step 154, e.g., activating switch 12. The system performs atleast four functions or steps as the result of this activation including(i) activating module interface port 18 which opens the fuel shut-offvalve 26, (ii) regulating the pressure of the incoming fuel using fuelregulator 60, (iii) activating purge valve system 109 and electricallyconnecting the fuel cell to the purge valve system to vent the anodeplenum of the fuel cells and (iv) connecting the fuel cell to theexternal load after the purge valve system is deactivated. Nothing elseis required from the user until system is shut-down. Thereafter, thesystem uses its own power from the fuel cell and automatically closesthe purge valve when purging is completed, e.g., using a SMA material,without active control by a microprocessor, sensors or a user. Thesystem then operates normally to produce electricity to run a load. Whenthe user wishes to shut the system down, s/he de-actives switch 12,which closes shutoff valve 26 by retracting module interface port 18 andde-activates the fuel cell circuitry.

FIG. 15 illustrates another method for operating a fuel cell. Inversemethod 158 is similar to method 152, except that in the activating step160 the system purges the fuel cell system or vents the anode plenum ofthe fuel cell and in the de-activating step 162 the purged system isarmed, i.e., inverse purge valve is opened when the system shuts down,as discussed above.

Demonstrating the passive aspect of the present invention, integratedfluidic interface module 10, method 152 and inverse method 158 do notrequire controller or microprocessor to operate, and no user interactionis necessary other than activating the ON/OFF switch. No external powersource, such as batteries, is required to start the system.Alternatively, methods 152 and 158 can be operated with active controlby a processor controlling an electrical valve, e.g., solenoid valve.

Another method of operating the fuel cell system is also described aboveusing the second valve 200 with SMA wire 124 to automatically turn thefuel cell system off, when it is idle or when no current is drawn fromthe fuel cell.

Another integrated fluidic interface module is illustrated in FIGS.16-17B. Similar to module 10, module 170 has movable module interfaceport 18 and tube 30 to open valve 26 on cartridge 20. Module 170 alsohas pressure regulator 60 and a flow manifold 172 fluidly connectingtube 30 to pressure regulator 60 and out of module outlet 92 to fuelcells 108.

Module 170 has a manual purge valve 174, which comprises a ball valveand ball actuator 176. The ball valve comprises sealing ball 178 biasedby spring 180 into sealing element 182. Actuator ball 176 sitsimmediately adjacent to sealing ball 178, and actuator ball 176 ispushed towards sealing ball 178 against the force of spring 180 to openpurge valve 174. Residual gases from the fuel cells enter module 170 atpurge port 138 and out of module 170 to vent at exit hole 184.

Switch 186 on module 170 is similar to switch 12, and is also used toextend and to retract module interface port 18. Switch 186 is pivotallyattached to the body of module 170. When a user pushes ON segment 14 ofswitch 186, this action moves actuator plate 188 in direction 190 andcompresses spring arm 52. This movement forces side knobs 44 on moduleinterface port 18 to ride up ramp or cam surface 192, thereby extendingor moving module interface port 18 in direction 50, as shown in FIG.17A. In this configuration, module interface port 18 advances towardscartridge 20 to open shut-off valve 26. When released, switch 186returns to its rest position due to spring arm 52 releasing its storedenergy, actuator plate 188 remains in the configuration shown in FIG.17A to keep module interface port 18 engages with cartridge 20.

When the user pushes OFF segment 16 of switch 186, this action movesactuator plate 188 in direction 190′. This movement forces sides knobs44 on module interface port 18 to ride down ramp or cam surface 192,thereby retracting or moving module interface port 18 in direction 50′,as shown in FIG. 17B. In this configuration, module interface port 18withdraws from cartridge 20 allowing cartridge shut-off valve 26 toclose.

Similar to module 10, switch 186 of module 170 also actuates manualpurge valve 174. Referring to FIG. 16, switch 186 is connected to purgeactuator 194. When the user pushes ON segment of switch 186, purgeactuator 194 also moves in direction 190 such that edge 196 of purgeactuator 194 moves over actuator ball 176 to open purge valve 174. Dueto the spacing between edge 196 and the rest of purge actuator 194, whenswitch 186 returns to the rest position edge 196 moves away fromactuator ball 176 and purge valve 174 closes. The duration of the periodthat purge valve 174 opens depends on the duration that switch 186 isheld in the ON position. Unlike actuator plate 188, purge actuator 194is fixedly connected to switch 186 so that these two components movetogether.

As described above, switch 186 actuates both the module interface port18 to open shut-off valve 26 and purge valve 174, as well as activatingthe fuel cell circuitry.

Any known fuel cell that consumes hydrogen can be used in fuel cellsystem 10. Preferably planar or side-by-side fuel cells are used.Suitable fuel cells are disclosed in U.S. Pat. Nos. 5,989,741,6,127,058, 7,632,587, 7,378,176 and 7,474,075, published U.S. patentapplication nos. 2002/0182475, 2004/0224190, 2006/0127734, 2007/0184330,2007/0196701, 2008/0233454, 2009/0081493, US2009123803, US2009169945,2009/0311561, 2009/0162722, 2009/0130527, 2011/0003299, US 2011/0165495and US2013059225 and published international patent application nos.WO2007020242, WO 2009/105896, WO 2011/079378, and WO 2011/079377, amongothers. These references are incorporated herein by reference in theirentireties.

Any known hydrogen storing or generating cartridges or system can beused. Such systems are disclosed in U.S. Pat. Nos. 7,674,540, 8,002,853,7,481,858, 7,727,293 and 7,896,934, and published U.S. patentapplication nos. 2010/0104481, 2011/0189574, 2011/0243836 and2009/0123342, among others. These references are incorporated herein byreference in their entireties. Fuel cartridges that contain liquid fuelcell fuels, such as butane or methanol, disclosed in U.S. Pat. Nos.7,172,825 and 7,059,582 can also be used with the various embodiments ofthe present invention.

Suitable pressure regulators are disclosed in U.S. Pat. No. 8,002,853,published international patent application no. WO 2011/127608 andpublished U.S. patent application nos. 2008/0233446, 2010/0104481 and2011/0212374. These references are incorporated herein by reference intheir entireties.

The fuel cell system 21 may also have a relief valve or a vent valve torelease hydrogen fuel or other fuel when the internal pressure exceeds acertain level.

The preceding detailed description refers to the accompanying drawingsthat depict various details of examples embodiments. The discussionaddresses various examples of the inventive subject matter at leastpartially in reference to these drawings, and describes the depictedembodiments in sufficient detail to enable those skilled in the art topractice the embodiments. Many other embodiments may be utilized otherthan the illustrative examples discussed herein, and many structural andoperational changes in addition to the alternatives specificallydiscussed herein may be made without departing from the scope of theinventive subject matter.

Throughout the preceding description, specific details are set forth inorder to provide a more thorough understanding of the disclosure.However, the inventions taught may be practiced without theseparticulars. In other instances, well known elements have not been shownor described in detail in order to avoid unnecessarily obscuring thedisclosure. The drawings show, by way of illustration, specificembodiments in which the inventions may be practiced. These embodimentsmay be combined, other elements may be utilized or structural or logicalchanges may be made without departing from the scope. Accordingly, thespecification and drawings are to be regarded in an illustrative, ratherthan a restrictive, sense.

All publications, patents and patent documents referred to in thisdocument are incorporated by reference herein in their entirety, asthough individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated referencesshould be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

The following parts list correlates the reference numbers used in thedrawings to the part names used in the specification.

REFERENCE # PARTS NAMES

-   -   10 Integrated fluidic interface module    -   12 Switch    -   14 ON segment    -   16 OFF segment    -   18 Module interface port    -   20 Fuel cartridge    -   21 Fuel cell system    -   22 Top side    -   23 Clamp on fuel cell system 21    -   24 Bottom side    -   26 Cartridge shut-off valve    -   28 Outer guard of cartridge port 18    -   30 Inner tube of cartridge port 18    -   32 Central post of valve 26    -   34 Gap on valve 26 to receive tube 30    -   36 Valve body of valve 26    -   38 Seal retainer on valve 26    -   40 Seal(s) in valve 26    -   42 Channel on cartridge 20 matching guard 28    -   44 Knob on module interface port 18    -   45 Detent on port 18    -   46 Yoke(s) on switch 12    -   47 Leg of detent 45    -   48 U-shaped end of yoke 46    -   50, 50′ Directions of movement of port 18    -   52 Spring arm on switch 12    -   54 Pivot boss on switch 12    -   56, 56′ Directions of movement of switch 12    -   58, 58′ Directions of movement of yoke 12    -   60 Pressure regulator    -   62 Inlet diaphragm    -   64 Shuttle    -   66 Outlet diaphragm    -   68 Large end of shuttle 64    -   70 Small end of shuttle 64    -   72 Shuttle housing    -   73 Shuttle housing vent    -   74 Spring inside pressure regulator 60    -   76 Outlet chamber    -   78 Inlet chamber    -   80 Inlet channel    -   82 Direction of inlet fuel flow    -   84 Inlet of pressure regulator 60    -   86 Outlet of pressure regulator 60    -   88 Outlet channel    -   90 Direction of outlet fuel flow    -   92 Module outlet    -   94 Feedback port    -   96 First feedback channel    -   98 Direction of feedback flow    -   100 Second feedback channel    -   102 Direction of feedback flow    -   104 Outlet chamber port    -   106 Thin covering films    -   107 Anode(s)    -   108 Fuel cell(s)    -   109 Semi-automatic purge valve    -   109′ Semi-automatic inverse purge valve    -   110 Purge shuttle    -   110′ Inverse purge shuttle    -   112 Sealing member for purge valve    -   113 Direction of sealing for purge valve    -   114 Sealing portion of purge shuttle 110    -   115 Direction of movement for purge shuttle    -   116 Open portion of purge shuttle 110    -   118 Shoulder of purge shuttle 110    -   120 Extension on purge shuttle 110    -   122 Notch on purge shuttle 110    -   124 Shape memory alloy (SMA) wire    -   126 Posts supporting wire 124    -   127 Channel on module 10 to store wire 124    -   128 Slit under shoulder 118    -   130 Channel on purge shuttle 110 for wire 124    -   132 Purge valve pusher    -   134 Fingers on pusher 132    -   135 PC board    -   136 Direction of purging gases    -   137 Output/USB port    -   138 Purge port on module 10    -   140 Purge channel(s)    -   142 Direction of purged gases    -   144 Double-ended purge shuttle    -   146 Module interface port with pusher 132    -   148, 150 Opposite surfaces on shoulder 118    -   152-156 Methods of operating the fuel cell system    -   170 Integrated fluidic interface module    -   172 Manifold in module 170    -   174 Manual purge valve    -   176 Actuating ball    -   178 Sealing ball    -   180 Spring    -   182 Sealing member    -   184 Purge exit hole    -   186 Switch    -   188 Actuating plate    -   190, 190′ Directions of movement of actuating plate 188    -   192 Ramp or cam surface    -   194 Purge actuator    -   196 Edge of purge actuator 194    -   200 Purge valve and automatic shut-off valve    -   200′ Purge valve    -   202 Outlet    -   204 End    -   206 Free end    -   208 Cantilever beam    -   209 Terminal end    -   210 Shoulder    -   212 Movable biased slider    -   213 End of slider    -   214 Main body    -   216 Forked legs    -   218 Hooked ends    -   220 Helical spring    -   222 Ledge    -   224 Spring arms    -   226 Spring arms    -   228 Flexible diaphragm    -   230 Extension    -   232 Notches    -   234 Direction    -   236 First ramp    -   238 Second ramp    -   240 Space    -   242 Periphery

According to yet another aspect of the present invention, flowrestrictors such as reduced diameter section(s) in the flow path orbends in the flow path can be inserted into the fluidic circuit. In oneexample, the flow restrictor can be positioned proximate to purge port138 to reduce or control the flow rate of the gas to be purged before itreaches purge valve 109, 109′ or 200. In other example, the flowrestrictor can be position upstream of the fuel cell or upstream ofoutlet 92 of module 10 and the flow restrictor can be upstream ordownstream of pressure regulator 60.

Additionally, although two outlets 92 to the fuel cell(s) are shown, thepresent invention is not limited to any number of fuel cells, which canbe one fuel cell or more than two fuel cells.

It is intended that the present specification and examples be consideredas exemplary only with a true scope and spirit of the invention beingindicated by the following claims and equivalents thereof, Otherembodiments of the present invention will be apparent to those skilledin the art from consideration of the present specification and practiceof the present invention disclosed herein. Additionally, components orfeatures of one embodiment can be utilized in other embodiments.

I claim:
 1. A method of operating a fuel cell system comprising at leastone fuel cell and an automatic shut-off valve, said method comprisingthe steps of (a) opening the automatic shut-off valve; (b) flowing fuelto the fuel cell system to produce an electrical current; (c) monitoringthe electrical current produced by the fuel cell and transmitted to aconsumer device, and (d) when said electrical current is reduced to apredetermined threshold, connecting the at least one fuel cell to aconductive element in the automatic shut-off valve to close saidshut-off valve.
 2. The method of claim 1, wherein the conductive elementcomprises a shape memory alloy.
 3. The method of claim 1, wherein instep (d) the fuel cell heats up the conductive element which retractsand moves the shut-off valve to a closed position.
 4. The method ofclaim 1, wherein the method further comprises a step of moving the purgevalve to an open position during at least one of the fuel cell system'sshut-down and start-up.